class InputRequired

class InputRequired extends ExposedFormPluginBase {
  
  /**
   * The filter format repository service.
   */
  protected FilterFormatRepositoryInterface $formatRepository;
  public function __construct(array $configuration, $plugin_id, $plugin_definition, ?FilterFormatRepositoryInterface $format_repository = NULL) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    if (!$format_repository) {
      @trigger_error('Calling ' . __METHOD__ . '() without the $format_repository argument is deprecated in drupal:11.4.0 and the $format_repository argument will be required in drupal:12.0.0. See https://www.drupal.org/node/3035368', E_USER_DEPRECATED);
      $format_repository = \Drupal::service(FilterFormatRepositoryInterface::class);
    }
    $this->formatRepository = $format_repository;
  }
  
  /**
   * {@inheritdoc}
   */
  protected function defineOptions() {
    $options = parent::defineOptions();
    $options['text_input_required'] = [
      'default' => $this->t('Select any filter and click on Apply to see results'),
    ];
    $options['text_input_required_format'] = [
      'default' => NULL,
    ];
    return $options;
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    parent::buildOptionsForm($form, $form_state);
    $form['text_input_required'] = [
      '#type' => 'text_format',
      '#title' => $this->t('Text on demand'),
      '#description' => $this->t('Text to display instead of results until the user selects and applies an exposed filter.'),
      '#default_value' => $this->options['text_input_required'],
      '#format' => $this->options['text_input_required_format'] ?? $this->formatRepository
        ->getDefaultFormat()
        ->id(),
      '#editor' => FALSE,
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitOptionsForm(&$form, FormStateInterface $form_state) {
    $exposed_form_options = $form_state->getValue('exposed_form_options');
    $form_state->setValue([
      'exposed_form_options',
      'text_input_required_format',
    ], $exposed_form_options['text_input_required']['format']);
    $form_state->setValue([
      'exposed_form_options',
      'text_input_required',
    ], $exposed_form_options['text_input_required']['value']);
    parent::submitOptionsForm($form, $form_state);
  }
  
  /**
   * Indicates that the exposed filter has been applied.
   */
  protected function exposedFilterApplied() {
    static $cache = NULL;
    if (!isset($cache)) {
      $view = $this->view;
      if (is_array($view->filter) && count($view->filter)) {
        foreach ($view->filter as $filter) {
          if ($filter->isExposed()) {
            $identifier = $filter->options['expose']['identifier'];
            if (isset($view->getExposedInput()[$identifier])) {
              $cache = TRUE;
              return $cache;
            }
          }
        }
      }
      $cache = FALSE;
    }
    return $cache;
  }
  
  /**
   * {@inheritdoc}
   */
  public function preRender($values) {
    // Display the "text on demand" if needed. This is a site builder-defined
    // text to display instead of results until the user selects and applies
    // an exposed filter.
    if (!$this->exposedFilterApplied()) {
      $options = [
        'id' => 'area',
        'table' => 'views',
        'field' => 'area',
        'label' => '',
        'relationship' => 'none',
        'group_type' => 'group',
        // We need to set the "Display even if view has no result" option to
        // TRUE as the input required exposed form plugin will always force an
        // empty result if no exposed filters are applied.
'empty' => TRUE,
        'content' => [
          // @see \Drupal\views\Plugin\views\area\Text::render()
'value' => $this->options['text_input_required'],
          'format' => $this->options['text_input_required_format'],
        ],
      ];
      $handler = \Drupal::service('plugin.manager.views.area')->getHandler($options);
      $handler->init($this->view, $this->displayHandler, $options);
      $this->displayHandler->handlers['empty'] = [
        'area' => $handler,
      ];
      // Override the existing empty result message (if applicable).
      $this->displayHandler
        ->setOption('empty', [
        'text' => $options,
      ]);
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function query() {
    if (!$this->exposedFilterApplied()) {
      // We return with no query; this will force the empty text.
      $this->view->built = TRUE;
      $this->view->executed = TRUE;
      $this->view->result = [];
    }
    else {
      parent::query();
    }
  }

}